CVE-2021-42890 in EX1200T
Summary
by MITRE • 06/03/2022
TOTOLINK EX1200T V4.1.2cu.5215 contains a remote command injection vulnerability in function NTPSyncWithHost of the file system.so which can control hostTime to attack.
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Analysis
by VulDB Data Team • 06/08/2022
The vulnerability identified as CVE-2021-42890 represents a critical remote command injection flaw within the TOTOLINK EX1200T router firmware version V4.1.2cu.5215. This vulnerability exists in the network time protocol synchronization functionality, specifically within the NTPSyncWithHost function of the system.so library component. The flaw allows remote attackers to execute arbitrary commands on the affected device by manipulating the hostTime parameter, which is processed within the NTP synchronization mechanism.
The technical implementation of this vulnerability stems from insufficient input validation and sanitization within the NTPSyncWithHost function. When the router processes network time synchronization requests, it fails to properly sanitize user-supplied hostTime values before incorporating them into system commands. This creates an environment where malicious actors can inject command sequences that will be executed with the privileges of the affected service. The vulnerability operates at the application layer and requires no authentication, making it particularly dangerous as it can be exploited remotely from any network location. The affected system.so library component serves as the primary execution point where the insecure command construction occurs, allowing for arbitrary code execution on the target device.
The operational impact of this vulnerability extends beyond simple remote code execution, as it provides attackers with complete control over the affected router. Once exploited, adversaries can gain full administrative access to the device, enabling them to modify network configurations, install malicious firmware, redirect network traffic, or establish persistent backdoors. The vulnerability affects the router's time synchronization functionality which is typically enabled by default, making the attack surface larger than many other command injection vulnerabilities. Network traffic can be intercepted and manipulated, and the compromised device can be used as a pivot point for attacking other systems within the local network. The vulnerability also poses risks to network security infrastructure as compromised routers can serve as entry points for broader network infiltration attempts.
Security professionals should implement immediate mitigation strategies including firmware updates from TOTOLINK, network segmentation to isolate affected devices, and monitoring for suspicious NTP traffic patterns. The vulnerability aligns with CWE-77 and CWE-78 categories, representing command injection flaws that permit arbitrary command execution. From an ATT&CK framework perspective, this vulnerability maps to techniques such as T1059.001 (Command and Scripting Interpreter: PowerShell) and T1021.001 (Remote Services: Remote Desktop Protocol) as attackers can leverage the compromised device for further network operations. Organizations should also consider implementing network access controls and firewall rules to restrict NTP traffic to trusted sources only, while maintaining regular vulnerability assessments to identify similar issues in other network infrastructure components. The affected device should be taken offline until proper security patches are applied and network monitoring systems are configured to detect potential exploitation attempts.